Exchanging Substances Part 2- Digestion

Question 1

What is digestion

Answer 1

Breaking down large insoluble molecules into small soluble ones
So they can be absorbed into the bloodstream
- extracellular

Question 2

What do the salivary glands do

Answer 2

Moisten food and begin digestion of maltose

Question 3

What does the oesphegus do

Answer 3

Transports food to the stomach

Question 4

What does the liver do

Answer 4

Produce bile

Question 5

What does the gall bladder do

Answer 5

Stores and releases bile into the small intestine
- neutralise stomach acid (optimum ph for enzymes0
- emulsifies lipids to increase sa

Question 6

What does the stomach do

Answer 6

Muscular tissue - mix up food
HCl, mucus, enzymes
Pepsin
Forms Chyme

Question 7

What does the pancreas do

Answer 7

Release digestive enzymes
With intestinal wall- produce alkaline slats- keep ph neutral

Question 8

What does the small intestine do

Answer 8

Breaks down food and absorbs nutrients

Question 9

What does the large intestine do

Answer 9

Absorbs water and ions

Question 10

What does the rectum do

Answer 10

Stores and expels faeces

Question 11

What is the difference between chemical and physical digestion

Answer 11

Physical - break down of larger into small food peices
Chemical - carried out by enzymes - hydrolysases

Question 12

What does amylase do and where is it stored

Answer 12

Breaks down starch into maltose (disaccharide )
Hydrolysis of glycosidic bonds
Made in salivary glands and pancreas

Salivary glands secrete amylase into the mouth where starch is hydrolysed

Question 13

What does Maltase do

Answer 13

Maltose
Into 2 alpha glucose

Question 14

What does sucrase do

Answer 14

Sucrose
Glucose and fructose

Question 15

What is lactase for

Answer 15

Lactose
Glucose and galactose

Question 16

Describe the trasport of lipids across membranes

Answer 16

The globule is emulsified by bile salts -> into small lipid droplets (mad eof monoglycerides and fatty acids)
These combine with bile slats to form micelles

These helps move monoglycerides and fatty acids towards the epithelium
Come into contact with cells. Micelles break down and monolgucerids, fatty acids diffuse across

One inside, monoglycerides and fatty acids are transport to the ER to recombine to form triglycerides

Continuing in the Golgi apparatus- triglycerides associate with cholesterol and lipoproteins called chylomicrons

Vesicles move two the cell membrane and move out by Exocytosis
- enter lymphatic capillaries called lacteals that are found at the centre of each villus
Chylomicrons pass into the bloodstream

Question 17

How do micelles help with lipid absorbtion

Answer 17

Make fatty acids more soluble in water
Carry fatty acids to the epithelial cells/ lining of ileum
Maintain higher concentration of fatty acids to cell
Fatty acids absorbed by diffusion

Micelles include bile salts and fatty acid s

Question 18

What is a chylomicrons

Answer 18

Triglyceride
+ cholesterol, + lipoprotein

Question 19

What does protease do

Answer 19

Breaks down protein into amino acids
Hydrolysising peptide bonds

Question 20

What re the differences between exo, endo and di peptidases

Answer 20

Endopeptidase act in the middle of protein/polypeptide
OR
Endopeptidase produces short(er) polypeptides/ increase number of ends

Exopeptidases act at end of protein/polypeptide
OR
Exopeptidase produces dipeptides/amino acids.

Dipeptidase acts on dipeptide/between two amino acids
OR
Dipeptidase produces (single) amino acids:

Question 21

What are the adaptations of th ileum for diffusion

Answer 21

Villi - large sa
Villi epithelium - Single layer - short diffusion
Muscle in villi- conc. gradient
Good blood supply